1. Field of the Invention
This invention relates to a sheet conveying mechanism for conveying a sheet such as photosensitive film with very high accuracy, and an imaging apparatus for recording an image on the sheet conveyed by the sheet conveying mechanism or reading an image recorded on the sheet.
2. Related Background Art
A sheet conveying mechanism as shown in FIGS. 9 and 10 of the accompanying drawings is known as a sheet conveying mechanism used in an image recording or reading apparatus for medical treatment. A roller unit 1 is such that the opposite shaft portions 5a and 5b of a sub-scanning roller 5 are supported by a pair of left and right bearings 3 and 4 mounted on a frame 2. The shaft portions 5a and 5b of the sub-scanning roller 5 are formed with grooves, in which ring-like stoppers 6 and 7 are fitted. A pre-load spring 8 is mounted between the stopper 7 and the bearing 4 so as to impart a moderate pre-load to the sub-scanning roller 5 in the axial direction thereof.
Also, on the shaft portion 5a side of the roller unit 1, a motor is constructed of a rotor 9 provided on the shaft portion 5a and a stator 10 provided on the extension of the frame 2, and an optical type encoder is constituted by a rotor 11 provided on the end portion of the shaft portion 5a and a detecting portion 12 provided on the end of the extension of the frame 2.
The roller unit 1 thus constructed is mounted on the frame 13 of an image recording or reading apparatus through the frame 2.